Underneath
by Kate Christie
Summary: "Blinking long and slow, she turns, puts her profile to the ornate brass mirror. A thin, white line pulls at her skin, fainter now, but still tight. Still angry." A season four Castle AU made up of brief episode additions. Complete. Late Castle Halloween Bash 2016 Entry. :)
1. Chapter 1

Underneath

Warm light filters through red silk, bounces off too-sharp angles, sinks slender ribs into shadow below the black edge of her cotton bra. Kate's eyes fall to the deep pile of burgundy carpet as her fingers reach around her back, mechanical, undoing its clasp. Her lips press tight and she inhales, shoulders caving to shuck off the only undergarment she has been able to tolerate since last May.

She wouldn't be in this stupid store if it weren't for her partner's complete lack of a filter. Closing her eyes, she's back in that musty basement, dreaming along with Castle's fairytale about that damn blue necklace. As he wove the story, "Kate's heart" _had_ quickened, and in a fit of wistful romance, she had remembered they were a week from Valentine's Day. Her chest had bloomed wide open at the possibility of feeling the least little bit… feminine.

On her way home, the red curtains and curly script in the warm shop window had appeared just as a gust of February wind blew her around the corner. The wrought iron railing, heavy brocade awning, perfectly coiffed mannequins posed just so - she half expected the suit passing by to be wearing a fedora. Her logic had shut down, and her heart had opened that creaky brass knob.

Blinking long and slow, she turns, puts her profile to the ornate brass mirror. A thin, white line pulls at her skin, fainter now, but still tight. Still angry.

 _Stupid._

Self-loathing stabs through her chest, bringing on a wave of nausea. How could she think she could do this? Stand here naked in a store and put on pretty things. Everything about her is still so very ugly. Her body is as broken as her soul.

Kate slides her arms back into the worn elastic straps, feels the satisfying catch of the hooks threading on the first try. At least now she can reach behind her back.

"Is everything working out for you, darlin'?" The warm, Southern alto wafts over the curtain. "I could get you another size. When's the last time you were properly measured?"

Not since before… Kate's eyes land on the small pile of satin and lace on the chair. She had grabbed her old sizes out of habit. She doesn't even know this body. Heart hammering, her gaze flicks to the mirror, narrowing on the pale, round pucker between her breasts.

"No, it's fine. I think I should just come back another day. I know you were about to close."

"Nonsense. We stay open late the week of Valentine's Day. I have my tape measure right here. May I come in?" Thin fingers backlit by the Tiffany lamp pause at the edge of the curtain.

"I-" Kate's eyes clamp shut, and she sees herself as she had that afternoon, through Castle's eyes, decked out in satin and lace, white gloves, jewels. It's a fantasy, and it will never come true, but for that instant, it had seemed possible. Just like everything with him. "Sure."

"I always feel better doing this myself. Not that I don't trust a woman to know her size, but it's sort of a point of pride in my profession, getting it just right." Smiling, the woman slips a tiny tape measure out of her pocket. Her light brown hair is done up in a chignon, her fingernails match her immaculate red wool suit, and her hands are blessedly warm.

Kate has no idea where to put her arms, much less her icy hands, as the woman threads the tape measure around her.

"Hands on your hips, darlin', and breathe for me."

Her head swims and she inhales, following orders.

"I'll be right back with just the thing."

Turning away from the mirror, she presses the heels of her palms against her eyes until everything goes to starbursts. It's a stupid lingerie store. She will never see this woman again. Why should she care that a perfect stranger has just seen her scars? Another wave of nausea swamps her.

 _Because she's the first person to see them who wasn't being paid to treat them._

Removing her hands, she takes the bra off again, throws it into the back corner with more force than necessary, and wraps her arms across her naked chest. Why does she have to be so fucking broken?

An inane voice inside her head whispers that she should have taken some salacious, naked photos before all this happened, so at least there would be some record of her body when it was still whole.

"Alright. I have options." There is a rush of red wool and hangers full of… gauzy, satiny, frilly things. "This set is almost as pretty as you." She hands Kate a bra and panties in sapphire blue.

Disappearing as quickly as she had entered, the woman leaves Kate alone with the hangers, dripping with jewel-toned scraps of fabric, and her image, dark and brooding, in the mirror. Taking a deep breath, she uncrosses her arms and reaches for the blue bra.

The straps slip on and she reaches back to do up the hooks, and soft, supple satin caresses her skin. There are no wires, nothing to catch or pinch, and as she turns to face the mirror, adjusting herself, she realizes the center panel comes up high.

Slipping the matching underwear on over her black cotton pair, she steps back. Her toes need polish. Legs could use a few more reps on the machines. But her hips flare out now. Oh, the underwear gives her back her curves. Not like they used to be, but the shape of her body isn't so… square. Almost… not ugly. Tears sting at the backs of her eyes, welling up as the pads of her fingers press in the center of her chest, hard enough to find the rough spot through the supple fabric. Still there. Always gonna be there. But not the first thing she sees.

Ignoring the price tags, she buys them, smiling at the knowing look in the eyes of the shop-owner.

"Now my merchandise comes with one condition. Enjoy it." The woman winks, handing over the small paper bag as she sees Kate out, locking the door behind her.

Five blocks and two flights of stairs later, Kate ignores her growling stomach and crosses straight to her bedroom. Dumping the contents of her top drawer across her bed, she lifts one or two of the mass-produced, underwire torture devices by their straps, lips pressing together in a tight line. She shoves the whole lot of them into a bag and stuffs them in the bottom of her wardrobe.

Setting the creamy paper bag in the center of her quilt, she stares at the gold-embossed script. She hasn't bought herself a present in a long, long time. Caving to the itch overtaking her fingertips, she reaches inside the bag, lifts the nest of red tissue, and slides one finger tip beneath the edge to release the heavy foil seal.

The lingerie matches her bedspread.

Why does that make her brain imagine his eyes the first time he sees her in it-?

Damn it. The lingerie matches his eyes. There's no help for it now. She loves... it.

Clipping off the tags, she washes the set in her sink with her cherry body wash and lays it out with nimble fingers over the lip of her bathtub. Her cheeks tingle, the muscles unused to so much smiling, as she chews through leftover Chinese and then climbs in bed.

When she walks into the bathroom to shower the next morning, she gives the set a sideways glance. Dreaming of all the ways Castle would invent to take it off of her has left her feeling… Empty. Dreams. That's all they will ever be. Her blue satin albatross stares back from its white, cast-iron perch. If only she hadn't washed it.

Carrying it back to her bedroom, she opens her now-empty top drawer and lays the pieces inside, slides the jittering wood cube closed along its antique track, and pulls serviceable cotton from her second drawer.

# * # * # * #

A/N: Thanks to Alex and she-who-shall-remain-nameless for shepherding this one. This story is complete and will be posted over the next 7 days.


	2. Chapter 2

Four hours since Gates took over the lockdown, and Kate has finished every last bit of paperwork she can dig up. The boys and Castle are nowhere to be found. As she stands to look at the board again, her eyes go unfocused. Nothing about this case, or their disappearing suspect, makes sense, and spending the night locked inside the precinct is not providing clarity. Maybe coffee will reset her brain. Who is she kidding, she wants the break room couch.

No lights on, blinds closed. A soft snore greets her as she nudges open the door. Light splays through the gap, silhouetting her across the tabletop, and catching on Castle's adam's apple. His head rests on the wall behind the couch, long legs stretching out into darkness on the floor.

Her hand grips the knob, and she starts to duck out, but his breath catches before she can shut the door.

"There's room, if you want to share, Kate."

God, he cannot use her first name when his voice is gravel rattling over sleep and sex.

"I'm sorry—I didn't mean to wake you." Light breaks across his profile, now upright, as she leans into the room. "I'll try a conference room."

"Ryan and Espo called the last one about an hour ago."

"You didn't offer to share with them?" Her smirk is lost in darkness.

"They started fighting over who got the middle seat. Come on. Gage is long gone. Gates is just being Gates now."

Butterflies ought to know better than to show up at a time like this.

The door snicks closed behind her, and the room sinks into black, broken only by the blue lights from Castle's coffee machine. They are enough to get her around the table without taking out a chair or a knee, and she sits on the end of the sofa opposite her partner, mirroring his pose, head back against the wall.

"How'd you get the vending machine lights off?"

"Unplugged them."

"Gates will not be happy if her morning Diet Coke is lukewarm."

"She's already bent out of shape with Gage walking out of here. And I heard her cancelling something on her cell with someone she called 'HoneyBear.'"

"God, Castle, I can never unhear that."

"Sorry - but I almost feel bad for her - hunting an escaped murderer is not exactly the best start to Valentine's Day." Castle turns to face her as he runs a hand through his hair.

"What?"

"It's past midnight. February 14th." His fingers lace together over his stomach.

"I hadn't even thought of it." Not since she had shut that top dresser drawer nearly a week ago. Staying late at the precinct every night had had nothing to do with avoiding the nudging, alto voice of its blue satin contents. A thought sends a wave of unease up through her gut. "Did you have plans?"

"No, I mean, not real ones." His nose points to the ceiling, and as he continues, her heart settles into her chest from its temporary residence in her throat. "No five-star reservations or anything. I kind of thought - it was stupid. No. No plans."

"What? What did you think?" And how has the air in the room gotten so thin?

Bright blue light catches on his eyelashes as they shutter closed.

"Maybe if we wrap up the case, we could grab a burger, or a beer." Shaking his head, he recants. "But you probably have plans. I said it was-"

"It's not stupid. It's not. I'd love to." Warmth bubbles up from her chest, floods her face, her fingers, her toes. Her muscles go lax, and then her hand is sliding down from her lap, fingers catching on the stitching along the old leather seams of the cushion between them. For one stuttering heartbeat, two, there is only the rise and fall of his chest. And then thick fingers thread between hers, curling under her palm and squeezing tight.

Damn it. Case or no case, she's wearing that lingerie.


	3. Chapter 3

Her fingers fumble with thick, wet wool catching on slippery buttons. Her shoes lay waterlogged, unsalvageable on the crumbling cement floor of the tiny warehouse bathroom. The coat slops down next. Maybe Murray can do something for it. No, if she gets even a whiff of the god-awful stale Hudson water - she won't wear it again anyway.

Dragging the turtleneck over her head wrenches her shoulder, already sore from yanking at the seat belt. Grunting with effort, she hears the crisp string of snaps when a seam gives way. God damn it.

Goosebumps never fade, they just supplant one another in fresh waves over bare skin that sticks to itself at every point of contact. She'd trade a month's salary for a scalding shower. At least a uniform had found a dry set of clothes for her.

Soaked belt, dripping pants, clinging socks all add to the pile, a meandering trail of river water now trickling from them toward the metal drain in the floor.

Kate reaches around her back to undo the slippery, blue clasp, and something inside her snaps. The tears fall, silent, as her breath catches. Collapsing in on herself, she folds in half, head hanging between her knees, arms wrapped around the backs of her thighs.

She almost died.

They almost died.

Her throat is raw from coughing out water, from emptying her stomach of as much of the Hudson as possible when she had awoken on the pier with Castle holding her head off the ground. He hadn't said a word, but she has no memory of getting free of the belt or the car, swimming to the surface, anything. And if she was out, he must have -

Inside her lips, the flesh tingles, bruised and swollen against the tip of her tongue.

A Valentine's kiss. She almost retches on her shoes.

Fucking Clara Strike - Sophia Turner - whatever. He was with her a whole fucking year.

She had a lot to teach me.

So much for being his muse, for being extraordinary-

No.

Kate drags in a shaky breath, bracing her hands on her knees and focusing on the soldered seam of corrugated metal where the ductwork meets the wall. The spiral stops now. She has a job to do. Her breathing slows as the digits countdown from ten in her mind.

Her pulse evens out, fingertips no longer tingling, and she rises, hooks her thumbs in either side of the blue satin underwear, and shimmies them over her hips. The fabric lands with a heavy plop, puddling around her feet.

She's gonna burn the damn lingerie.


	4. Chapter 4

"Beckett."

"Katherine, I hope I'm not interrupting an interrogation. This is Richard's mother."

"I wish there were something to interrupt, Martha. We're a little stuck on our case at the moment." Kate turns from the murder board and heads for the back stairwell.

"Oh good! I mean, of course it's never good if a killer is on the loose - what I meant was, I'm so glad I'm not interrupting. You see, I'm staging a one woman show based on my life, and we're premiering it here, at the loft. An intimate little gathering for family and a few dozen of my closest friends."

"That's wonderful. Congratulations." Kate's brows knit as she pushes through the exit door and steps onto the landing.

"It's an allegory of sorts- an artist finding meaning amidst the nameless, faceless masses of New York. I think it has a little something for everyone."

"It sounds really fascinating." Kate's hip presses into the metal railing, and she takes one step down, hanging the heel of her boot off the edge of the one above.

"But I digress, the reason I called was to say that I would be honored to have you in attendance."

"I - wow." She drops to sit on the step, heart doing a funny skip under her ribs. "Um, when is it?"

"Tomorrow night. Eight o'clock sharp. There will be champagne. Hors d'oeuvres. Mood lighting. In fact, you and Richard should make a date of it."

"I…" Her stomach flips, palm pressing into the rough ridges of exposed brick.

"I haven't told him yet, but Richard may need some moral support. He features prominently in my metamorphosis from actress to mother, and you know how he gets when hints of his boyhood and those awkward teen years come up."

A single note of laughter escapes despite her best efforts to squelch it. The stories from their family dinner after the bank incident had been priceless blackmail material.

"It would mean so much to have you there, dear. A comrade in arms. A fellow career woman, weaving her way through the harsh realities of a cold city, all alone."

"I -" Warmth bubbles up at the older woman's words, dramatic, as always, but with a ring of sincerity even the actress couldn't feign. "I'd be honored, Martha."

"Lovely - it's a date. Well, I should let you get back to defending this fair city. Oh, no need to dress up - just come as you are, darling, fabulous as always."

Standing at her dresser in the dark the next morning, Kate's hand reaches for the pull on her top drawer, stops just short and balls into a fist. Try as she might, she had not been able to throw the damn lingerie out the week before. After two washes, there had been nothing left of the Hudson. That's more than she can say about any of the rest of her clothes. More than she can say about her own skin. She still smells the river in her hair every time she showers.

Her fingers clutch the cold brass of the knob and tug.

Fuck it. She's going on a date with Castle.


	5. Chapter 5

Standing in his home, glass of golden bubbles in her hand, Kate draws in a shaky breath. She can feel the give of the straps under her turtleneck, the gentle press of the band against her ribcage. Her nipples strain against soft satin. Castle is off with his mother and daughter, leaving her alone to mingle. Or avoid mingling. Her stomach cannot handle small talk.

Night presses close through the wall-high windows. Warm light streams out from the room, battling back the darkness. On the sidewalk below, a couple dashes by, rushing for the corner, gloved hands knotted together, never parting despite the cold and their speed. Want curls around her heart, squeezes tight.

"Detective Beckett?" Alexis stands, backlit by kitchen lights, between Kate and the now-occupied rows of seats. "We're about to start."

"Oh, I'm sorry, I'll find a seat."

"You're up here. By me and my dad. Gran insisted." Her smile doesn't quite reach her eyes as she holds out an arm to guide Kate to the front row. "Have you met Marcus O'Neill? The writer who helped Gran with the play."

Strong fingers grip her hand as the fresh-faced writer stands from his spot at the end of the row of chairs.

"Hi, I'm Kate, I'm a friend of-"

"The family. Kate's the detective my father follows for background on his books." Alexis takes the chair on the other end of the row, leaving an empty spot between herself and Kate.

"So good to meet you. Martha has told me so much about you."

"She has?"

"You know Martha and her gift with words. I feel like I practically know you already."

Alexis has gone silent, checking her phone, so Kate turns to Marcus, plasters on her best social smile.

"She does have a flair for storytelling."

"To say the least. I've enjoyed writing this piece - she's led a fascinating life. I've learned so much about what it means to struggle for your art, to live every moment to its fullest."

"We could all use a lesson in that." Kate's smile turns genuine at the beaming playwright's enthusiasm.

"It couldn't have been easy, raising a child in this city, alone. It would have been easy to be jaded. But she just kept going - putting one foot in front of the other. That's what I like best about her life, this show. It's not about fate. Whatever hand life deals you, only you have the power to write your happy ending."

Air freezes in her lungs, and the room narrows to the oval of his face, the shock of chestnut hair, the point of his chin. All of it, her whole life story, lays out before her. Her mother smiles back from some slippery moment of memory, "But the greatest of these is love."

"Beckett!" Castle dashes out of the office door, eyes frantic until he finds her, staring vacantly over the shoulder of the playwright. "We got the wrong killer."


	6. Chapter 6

"Thank you so much for inviting me, Martha. You were spectacular."

"Oh thank you, thank you. Of course I could never have done it without these two." Martha wraps one arm each around her smiling son and granddaughter and plants a loud smooch on their foreheads before wrapping Kate in tight hug. The warm hum in her ear sounds suspiciously like, "Love you," but Martha pulls away to climb the stairs like she's said nothing at all, with Alexis trailing behind her.

Kate stands stock still, Martha's words echoing and mingling with another quiet whisper, bright blue sky and green grass crystal clear inside her memory, all layered under Marcus' tenor.

 _"Only you have the power to write your own happy ending."_

"Hey." Castle's voice is soft and close, snapping Kate out of her daze. Turning, she finds him smiling, hair a little askew from the dozens of times he had run a hand through it in response to a line about his childhood. Rumpled. Relaxed. At home. That sight is so rare, she can't help smiling back. "What?"

Stepping into his chest, she reaches up, threads her fingertips through the unruly strands.

"Your family is never boring."

"I'm glad you recognize that now…"

"As opposed to…?"

Big blue eyes flick back and forth between hers.

"La-" his voice cracks and he clears his throat, "Later."

Clamping down on the laugh, she keeps her reaction to a tightly-pressed smile, doesn't step back.

"You wanna watch a movie? I could make some popcorn, we could finish the champagne. I suddenly have the urge to see some John Woo."

Lacing her fingers with his, she takes a step back, toward the kitchen and the sweating green bottle on the counter.

"What's the matter, Castle, not feeling the fairy tales anymore?"

"Maybe I've just had enough fiction for one night." His voice has gone serious, eyes warm, steady and watching her without hesitation.

"Agreed. I'm ready for something real."

Soft, warm lips press against hers as she stands on tip-toe, finally, finally giving in.


	7. Chapter 7

Thick, gloved fingers intertwine with hers, warming her hand from the blustery wind. Streetlights flicker to life as the setting sun sinks the avenue into shadow. One final ray glints off a storefront near the corner, and Kate hesitates.

"Hey, could you survive a few more minutes without food?"

"There's only one thing I'm more hungry for than food-"

"Yes, I know, and I promise this stop will feed that appetite, too."

"Now I'm intrigued."

Tugging him behind her through the creaking door, she stops short when her eyes land on a young brunette sitting behind the register.

"Good evening. Can I help you find anything?"

Kate smiles back as she thanks the woman and waves her off, heading for the first display rack of nighties and slips.

"What do you think? Wanna buy me a present?"

"I think I'm the one getting a present for your birthday." His eyebrows waggle. "Do I get to pick it out?"

"Why else would I have brought you in here?"

Trailing one finger down the plunging neckline of a black satin set hanging at eye level, he mouths at her in silence.

"Best present ever."

Castle bounces on the balls of his feet, crowding behind her as she slides the red silk curtain open. Taking a seat opposite the ornate mirror, he settles in to watch her disrobe.

Blouse buttons pop open one at a time, a practiced, one-handed move after almost nine months of stripping for him. The purple lace bra and panties under her staid blue cotton shirt and gray dress slacks shouldn't surprise him-he watched her put them on just before sunrise. But his eyes have blown to big, black saucers nonetheless. Her heels stay on as the fine wool pools at her feet.

Kate takes her time reaching around, turns her profile to him as she arches her back and unhooks her bra. He smirks as she lets one strap fall over the peak of her shoulder, winking before she slips her arm through. Facing away from him, and into the mirror, she snags either side of her underwear with her thumbs and inches them down, watching through the mirror as he shifts, then leans back against the slick leather chair.

His chest has ceased to expand, nostrils flaring and lips parting on his aborted inhale as he tracks the progress of the cool satin negligee over her naked skin. It fits like a glove, feels like sinning on Sunday as she slinks across the room to stand between Castle's spread knees.

"You like it?"

Leaning forward, he twines his arms around her, hands catching and stroking her thighs through the slippery silk. He has to clear his throats twice before he can answer. Maybe boudoir photos are in order for his next birthday...

"I'd like to take it off of you. Very, very slowly. With ice cubes."

His body presses tight to her back at the register, and from the feel of him, she knows dinner will have to wait a little longer once they get home. The young woman packs her purchase gently in scarlet tissue, fixing the foil seal across the seam before she tucks it into the cream-toned bag.

Lilting Southern alto echoes inside her mind.

"Enjoy it."

Kate smiles at the memory. She would have winked back tonight.

"There's another saleswoman who works here, mid-fifties, Southern accent-I didn't get her name though."

"It's mostly just me and my sister, but sometimes we hire a college kid for the Christmas rush."

"This was around Valentine's Day. She was about your height, brown hair, wore a suit-" her gaze flicks around the room, as if the woman might appear from the ether. Her eyes land on a framed newspaper article hanging behind the register-the photo at the top is her saleswoman, right down to the string of pearls.

"There. That's her."

The young woman knits her brow as she glances behind her.

"You mean Dora?"

"I guess so-do you know when she'll be back?"

Soft eyes and a gentle smile frame the clerk's answer, as she folds Kate's receipt and adds it to the bag, embossed with "Dora's" in curly, gold script.

"I'm sorry to say, she hasn't been here in almost thirty years. This place was Mimi's pride and joy. She opened it back in 1947 and worked here until the day she died."

# * # * # * #

A/N: Thanks so much to Alex and *** for the excellent beta and to E for the beautiful artwork. Also, thanks to Travis and the Castle Halloween Bash for keeping my twist a secret. Read more of the original Lingerie Fic in "Enlightenment" and its M-rated companion on my ffn page. Thanks to all for reading, reviewing, and promoting. Happy Halloween!

Twitter: Kate_Christie_

Tumblr: KathrynChristie dot tumblr dot com


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